refactor: address second round of PR review feedback

- Remove unnecessary `async` from `handshake()` and `connect()`
- Remove commented-out `reserved` variable in `handleConnectResponse()`
- Add NODE_DEBUG documentation to Socks5ProxyAgent.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Matteo Collina <hello@matteocollina.com>

Author: mcollina

docs/docs/api/Socks5ProxyAgent.md

@@ -213,6 +213,16 @@ Implements [`Dispatcher.dispatch(options, handlers)`](/docs/docs/api/Dispatcher.
 
 See [`Dispatcher.request(options [, callback])`](/docs/docs/api/Dispatcher.md#dispatcherrequestoptions-callback).
 
+## Debugging
+
+SOCKS5 proxy connections can be debugged using Node.js diagnostics:
+
+```sh
+NODE_DEBUG=undici:socks5 node script.js
+```
+
+This will output detailed information about the SOCKS5 handshake, authentication, and connection establishment.
+
 ## SOCKS5 Protocol Support
 
 The Socks5ProxyAgent supports the following SOCKS5 features:

lib/core/socks5-client.js

@@ -142,7 +142,7 @@ class Socks5Client extends EventEmitter {
   /**
    * Start the SOCKS5 handshake
    */
-  async handshake () {
+  handshake () {
     if (this.state !== STATES.INITIAL) {
       throw new InvalidArgumentError('Handshake already started')
     }
@@ -262,7 +262,7 @@ class Socks5Client extends EventEmitter {
    * @param {string} address - Target address (IP or domain)
    * @param {number} port - Target port
    */
-  async connect (address, port) {
+  connect (address, port) {
     if (this.state === STATES.CONNECTED) {
       throw new InvalidArgumentError('Already connected')
     }
@@ -308,7 +308,6 @@ class Socks5Client extends EventEmitter {
 
     const version = this.buffer[0]
     const reply = this.buffer[1]
-    // const reserved = this.buffer[2] // Not used
     const addressType = this.buffer[3]
 
     if (version !== SOCKS_VERSION) {

test/socks5-client.js

@@ -307,9 +307,7 @@ test('Socks5Client - connection refused', async (t) => {
   const client = new Socks5Client(socket)
 
   client.on('authenticated', () => {
-    client.connect('example.com', 80).catch(() => {
-      // Error is handled in the error event
-    })
+    client.connect('example.com', 80)
   })
 
   client.on('error', (err) => {